Thin client t510: Display issue

[SilkBC]

Hello,

I hope someone has some ideas about this one.  I have a client who has a bunch of HP t510 thin clients.  I recently re-imaged them using ThinUpdate and they are on the Linux-based ThinPro OS now (version 5.2; higer version not available for this model).  All seemed to be fine, but several of them have developed "blockiness" or "artefacts" when they connect to their terminal server.

Through some tedious troubleshooting, I have been able to determine that it has something to do with at least some of the monitors, but they have all sorts of different kinds of monitors.  I was able to narrow the issue down to the monitors because I found a unit where the artefacts did not occur (call this "Unit A"), and it was connected to different monitors.  If I swapped the unit with one of the ones where the artefacts was occurring. the artefacts started occurring on "Unit A" and "disappeared" from the unit I swapped out (and connected to the monitors "Unit A" had previously been connected to).  The only difference was the monitors, and this issue is occuring on many, but not all of the t510s.

I am not sure if it is a resolution issue, a refresh issue, or something else.  I have tried different resolutions and refresh rates, but the OS just seems to keep using the best auto-detected resolution and refresh rate, even if I create a display profile with set resolution and refresh rate and assign it to the monitors in the Display Preferences.

I found a post where something similar was occurring with an HP thin client, but on a Citrix connection, but the symptom seemed pretty much the same.  The solution in that case was to update the graphics driver, but it appears they were running the Windows Embedded OS (which isn't available for the t510 via ThinUpdate, for some reason)

Any insights or other suggestions greatly appreciated.